Neutrophil Gelatinase–Associated Lipocalin in Dogs with Naturally Occurring Renal Diseases

BACKGROUND Neutrophil gelatinase-associated lipocalin (NGAL) is released from renal tubular cells after injury and serves in humans as a real-time indicator of active kidney damage, including acute kidney injury (AKI) and chronic kidney disease (CKD). However, NGAL concentrations in dogs with naturally occurring AKI or CKD rarely have been explored in detail. HYPOTHESIS/OBJECTIVES The goal of this study was to evaluate whether NGAL can serve as a useful biomarker in dogs with naturally occurring renal disease. ANIMALS Client-owned dogs with renal disease (57) and control dogs without any disease (12) were examined. METHODS Serum NGAL (sNGAL) and urine NGAL (uNGAL) concentrations were measured in each animal by a newly developed ELISA system. Demographic, hematologic, and serum biochemical data were recorded. Survival attributable to AKI and CKD was evaluated at 30 days and 90 days, respectively. RESULTS Serum and urine NGAL concentrations in azotemic dogs were significantly higher than in nonazotemic dogs and were highly correlated with serum creatinine concentration (P < .05). Among CKD dogs, death was associated with significantly higher sNGAL and uNGAL concentrations compared with survivors. Receiver-operating characteristic curve (ROC) analysis showed that sNGAL was better than serum creatinine concentration when predicting clinical outcomes for CKD dogs (P < .05). The best cutoff point for sNGAL was 50.6 ng/mL, which gave a sensitivity and a specificity of 76.9 and 100%, respectively. Furthermore, dogs that had higher concentrations of sNGAL survived for a significantly shorter time. CONCLUSION sNGAL is a useful prognostic marker when evaluating dogs with CKD.